P. de Cocq

Usability of normal force distribution measurements to evaluate asymmetrical loading of the back of the horse and different rider positions on a standing horse

Pressure measurement devices in equine sports have primarily focused on tack (saddle pads and saddle fitting methods). However, saddle pressure devices may also be useful in evaluating the interaction and distribution of normal forces between the horse and rider, including rider position and riding technique. This study examined the validity, reliability, repeatability and possibilities of using a saddle pressure device to evaluate rider position. All measurements were performed using a standing horse. Validity was tested by calculating the correlation coefficient between measured normal force and the weight of the rider. Repeatability was tested by calculating intra-class correlation coefficients. The use of normal force measurements to evaluate horse-rider interaction was tested by adding a known weight to saddle or rider and collecting measurements with the rider sitting in four different positions. The device was found to be valid and reliable for force measurements when the measurement device was not replaced. The system could be used to determine the expected differences with added weight and in different rider positions. The normal force distribution measurement device proved to be a valid and reliable tool for studying the interaction between a rider and a static horse provided it is positioned carefully and consistently relative to both the horse and the saddle.

The effect of rising and sitting trot on back movements and head‐neck position of the horse

REASON FOR PERFORMING STUDY During trot, the rider can either rise from the saddle during every stride or remain seated. Rising trot is used frequently because it is widely assumed that it decreases the loading of the equine back. This has, however, not been demonstrated in an objective study. OBJECTIVE To determine the effects of rising and sitting trot on the movements of the horse. HYPOTHESIS Sitting trot has more extending effect on the horses back than rising trot and also results in a higher head and neck position. METHODS Twelve horses and one rider were used. Kinematic data were captured at trot during over ground locomotion under 3 conditions: unloaded, rising trot and sitting trot. Back movements were calculated using a previously described method with a correction for trunk position. Head-neck position was xpressed as extension and flexion of C1, C3 and C6, and vertical displacement of C1 and the bit. RESULTS Sitting trot had an overall extending effect on the back of horses when compared to the unloaded situation. In rising trot: the maximal flexion of the back was similar to the unloaded situation, while the maximal extension was similar to sitting trot; lateral bending of the back was larger than during the unloaded situation and sitting trot; and the horses held their heads lower than in the other conditions. The angle of C6 was more flexed in rising than in sitting trot. CONCLUSIONS AND CLINICAL RELEVANCE The back movement during rising trot showed characteristics of both sitting trot and the unloaded condition. As the same maximal extension of the back is reached during rising and sitting trot, there is no reason to believe that rising trot was less challenging for the back.

Quantification of surface EMG signals to monitor the effect of a Botox treatment in six healthy ponies and two horses with stringhalt: preliminary study.

REASONS FOR PERFORMING THE STUDY Therapeutic options for stringhalt in horses are limited, whereas medical experiences with botulinum toxin type A (Botox) have been positive. To evaluate its effectiveness in horses, surface electromyography (sEMG) signals before and after injection need to be quantified. HYPOTHESIS Treatment of healthy ponies and cases with Botox should reduce muscle activity in injected muscles and reduce spastic movements without adverse side effects. METHODS Unilaterally, the extensor digitorum longus, extensor digitorum lateralis and lateral vastus muscles of 6 healthy mature Shetland ponies and 2 talented Dutch Warmblood dressage horses with stringhalt were injected (maximum of 400 iu per pony and 700 iu per case; 100 iu in 5 ml NaCl divided into 5 injections) with Botox under needle EMG guidance. Surface EMG data were evaluated using customised software, and in the individuals gait was analysed using Proreflex. Statistical analysis was performed using mixed models and independent sample t test (P < 0.05). RESULTS Surface EMG signals were quantified using customised software. The area under the curve (integrated EMG) in time was used as variable. It became significantly reduced in injected muscles after injection of Botox in normal ponies (P < 0.05). This effect was present from Day 1 until Day 84 after injection. In the 2 cases, after injection of 3 muscles, the integrated EMG in time became significantly reduced in all 3 muscles. Kinematic measurements confirmed reduction of frequency and amplitude of hyperflexing or hyperabducting strides of the affected hindlimbs. The duration of effect was also seen in the cases until around 12 weeks after injection. CONCLUSIONS AND POTENTIAL RELEVANCE After EMG guided injections of Botox, sEMG signals recorded from injected muscle were reduced, which proves this to be a useful tool in statistically evaluating a treatment effect. The positive results of this pilot study encourage further research with a larger group of clinical cases.

Saddle and leg forces during lateral movements in dressage.

REASONS FOR PERFORMING STUDY In the equestrian world it is assumed that riders use changes in weight distribution and leg forces as important instruments to give horses directions about speed and direction of movement. However, the changes of these forces have never been quantified. OBJECTIVES To investigate the distribution of normal forces (perpendicular to surface) underneath the saddle and of normal forces exerted by the riders legs during lateral movements. MATERIALS AND METHODS Eleven riders performed 3 different exercises: riding straight ahead, shoulder-in and travers at trot. Three saddle force systems were used simultaneously. The magnitudes of the forces were summed for the total area, the inside and the outside half of the saddle and inside and outside leg. Mean and maximum summed forces were analysed statistically. RESULTS The saddle forces showed a rhythmic pattern but leg forces were more irregular. Mean total saddle force was lower (P = 0.006) when riding straight ahead (671 ± 143 N) than when riding shoulder-in (707 ± 150 N) or travers (726 ± 165 N). Mean inside saddle force was higher (P = 0.003) when riding travers (468 ± 151 N) than when riding straight on (425 ± 121 N) or shoulder-in (413 ± 136 N). Maximum outside leg force was higher (P = 0.013) when riding travers (47.2 ± 33.9 N) than when riding straight on (31.6 ± 24.1 N) or shoulder-in (34.2 ± 27.3 N). CONCLUSION The study helps to give a biomechanical background to well established but intuitive horse riding techniques.